Manipulation method and device for a foundry

ABSTRACT

A foundry manipulation method and device for foundry castings or equipment and in particular for molten metal, constituted by a frame 1 supporting an arm 9 to one of the ends of which there is fitted a member 11 for supporting castings, equipment or metal. According to the invention, the frame 1 comprises a fixed part 2 and a mobile part 3 rotating relative to part 2 about a vertical shaft. The support member 11 is hinged to end of the arm 9, arm is hinged in the vicinity of its other end 9b to the top of mobile part 3 about a horizontal pin 12 in such a manner that the support member 11 passes to a position directly above vertical shaft 3 during the movement of the arm 9 about its hinge 12, means 19 being provided to maintain support member in a vertical position, whatever the inclination of the arm.

SCOPE OF THE INVENTION

The invention relates to a transfer and manipulation device for foundryaccessories, and more precisely for a light alloy casting ladle.

PRIOR ART

In the foundry field, and in particular the light alloy foundry field,it is known to use what are currently called robots for carrying out theoperations involved in manipulating castings, mould parts, cores ormolten metal, from a first charging zone to a second discharge zone.They are thus used for example in order to withdraw such metal from oneor more fixed molten metal holding furnaces using a ladle, transferringthe full ladle to directly above one or more other stations in whichmoulds are prepared, by means of a device which automatically moves theladle between the furnaces and moulds, pouring the metal into thesemoulds and returning the ladle to directly above a furnace in order torecommence this operation. Secondary stations can be provided about suchrobots for carrying out maintenance on the ladle or the manipulatedelements, and the device is either automatically or manually controlledin bringing the ladle level with these stations.

Known devices for carrying out the manipulation movements are of varioustypes. They are mainly mechanisms comprising bridges on which arehorizontally moved the vertical mobile devices carrying the ladle, orarms hinged to rotate horizontally about a column and comprising attheir free end a support or gripping member which can be driven with avertical movement relative to the arm or column, if necessaryaccompanied by a traverse movement along the arm.

DESCRIPTION OF THE INVENTION

The present invention relates to a robot for manipulating foundrycastings or equipment, and in particular molten metal for makingcastings, of the type in which the transfer operation is carried out bya support or gripping member carried at the end of an arm which canrotate in a vertical plane about a horizontal pin, said pin beingcarried by a part of a frame which rotates horizontally.

More particularly, it firstly provides a method for operating the arm inwhich, separately and consecutively, the arm is first elevated byrotation in said vertical plane until the support or gripping member isdisposed directly over the vertical shaft of rotation of the rotatingpart of the frame, this part is then rotated horizontally about saidvertical shaft, and finally the arm is made to continue its rotation inthe same direction of rotation about its hinge in order to cause it tolower.

The invention secondly provides a manipulation device constituted by aframe supporting an arm, at one end of which there is attached agripping or support member for the elements to be manipulated. The framecomprises a fixed part and a mobile part, rotatable relative to saidfixed part about a vertical shaft. Said member is hinged to said end ofthe arm. Finally, said arm is hinged in the vicinity of its other end tothe top of said mobile part, about a horizontal pin. Means for drivingthe arm about its hinge are disposed between said arm and said rotatablepart of the frame in such a manner that the arm can be rotated throughabout 180°, the support or gripping member being able during itsmovement to describe substantially a vertical semicircle about thehorizontal plane passing through said hinging pin. Means are providedfor keeping said support member in a fixed position, for examplevertical, in particular in the case of a casting ladle, whatever theinclination of the arm.

In a preferred embodiment, the means for driving the arm about its hingeare constituted by a cylinder rigid with the rotating part of the frame,its rod comprising a rack cooperating with a pinion rigid with the arm.The mobile part of the frame is rotated relative to the fixed part by adrive member of the cylinder type rigid with the fixed part, the rod ofwhich comprises a rack cooperating with a drive pinion for the mobilepart. It is advantageous if said arm is prolonged beyond its hingerelative to the support member, and has hinged to one of its ends therod of a pneumatic compensating cylinder, itself hinged to the mobilepart of the frame. Finally, a secondary arm hinged about said horizontalhinging pin and fitted at its end with proximity detection probes,extends along said arm.

The invention will be more apparent from the description givenhereinafter by way of non-limiting example, which will enable theadvantages and secondary characteristics to be deduced, and which ismade with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation of a preferred embodiment of the device accordingto the invention, in its casting robot version.

FIG. 2 is a plan view of FIG. 1.

These figures show a frame 1 comprising a fixed casing 2 embracing avertical shaft 3. The casing is fixed to the ground by a bed-plate 4. Atthe level of a box 5, the vertical shaft 3 comprises an externallytoothed wheel, not shown, which cooperates with a toothed rod, equallynot shown, of a hydraulic device 6 of the cylinder or telescopiccylinder type. Two cylinders 6a and 6b are in fact shown here, fixed endto end, the rod of the cylinder 6a being fixed at its end to a support 7rigid with the box 5, and thus with the casing 2, the rod of thecylinder 6b being toothed and forming a rack which cooperates with thetoothed wheel rigid with the shaft 3.

It can be seen that by feeding one and/or the other of the double actingcylinders, the vertical shaft 3 can be rotated in one direction or theother.

At its top, the vertical shaft 3 is fitted with a part 8 having a hollowportion 8a offset relative to said shaft. The part 8 constitutes thefixing platform for the entire upper equipment of the device accordingto the invention. This equipment comprises an arm 9 having one end 9a inthe form of a fork which carries a withdrawal ladle 11 hinged at 10. Themaximum distance apart L (FIG. 2) of the two arms of the fork exceedsthe maximum outer dimension 1 of the withdrawal ladle 11. This ladle isin particular a ladle with a stopper rod, the control mechanism forwhich is shown at 11a. An overpressure, a negative pressure or a neutralatmosphere can be provided in said ladle, which is closed by a cover11b.

In the vicinity of its other end 9b, the arm 9 is hinged to the part 8about a horizontal hinging pin 12. This pin is shown carried by theoffset portion 8a of the part 8 for dimensional reasons and forsimplifying the assembly. However, there is nothing to prevent disposingthe pin 12 directly above the shaft 3, other than the fact that it wouldbe necessary to provide a platform 8 of more complex shape to leave theclearances necessary for allowing the various movements of the hingedparts.

It can be seen from the figures that in this respect the end 9b of thearm 9 is extended beyond the hinging pin 12 relative to the ladle 11.This end constitutes a point at which the rod 14a of a pneumaticcylinder 14 is fixed by a hinge 13, its body being hinged at 15 to thetwo flanges which the portion 8a of the part 8 comprises at its bottom.

It should be noted that the pin 12 rotates rigidly with said arm 9, andis supported by bearings 16 rigid with the platform 8. In a casing 17,the pin 12 is fitted at one of its ends with a toothed wheel whichcooperates with a rack. This rack is in fact constituted by the rod of ahydraulic cylinder 18, the body of which is fixed to the part 8. Thuswhen this cylinder is fed, it rotates the pin 12 and thus drives the arm9 about its horizontal hinge on the part 8. The amplitude of therotation can thus be at least 180°.

At the other end of the pin 12, the bearing 16 is fitted with a pinion19a about which a chain 19b can pass. Said chain, which is endless, alsopasses about an identical pinion 19c provided at the end of the hingingpin 10 of the ladle--with which it is rigid--at the arm end 9a. Thischain and its two pinions are shown in phantom in the figure as they areenclosed in a protection casing 19. Thus, as the arm 9 rotates with itspin 12 held in the chain, the chain winds about the fixed pinion andcauses the pinion rigid with the pin 10 to turn through an angle equalto the angle of inclination through which the arm has travelled, so thatthe ladle 11 preserves its initial orientation, i.e. its verticality.

Finally, a second arm 20 is provided along the arm 9. This latter ismounted so that it rotates about the pin 12 by means of one of its ends,while its other end carries a support 21 for probes 22 which detect thelevel of the bath in the furnace. This secondary arm is urged by aspring 23 against a stop 24 rigid with the arm 9. However, a fixed stop25 provided on a member rigid with the piece 9 (in this case the casing17) retains said arm 20 in a substantially vertical position so that itdoes not follow the rotation of the arm 9 beyond this position in ordernot to obstruct the casting zone.

The operation of the robot described heretofore is as follows. It willbe firstly assumed that in the position shown in FIG. 1 the castingladle 11 is plunged into the furnace for withdrawing metal. Afterclosing the ladle by means of its stopper rod, and possibly putting theladle under vacuum by means of the control mechanism 11a and a controldevice 30 the arm 9 is raised by means of the cylinder 18 and cylinder14.

The effect of the pneumatic pressure applied to the cylinder 14 is toretract the rod 14a to provide a torque which is added to the liftingtorque applied by the hydraulic cylinder 18. The ladle 11 preserves itsvertical position during this lifting by virtue of the chain enclosed inthe casing 19. The ladle thus arrives directly over the shaft 3. At thismoment, its movement is halted by an arm position detector, not shown,and the hydraulic cylinder mechanism 6 is fed in order to rotate theshaft 3 through a predetermined amount. The feed for these cylinders ispreset on a known control device for the angular indexing of the robot.It should be noted that by carrying out this indexing operation when thecasting ladle is directly above the vertical shaft 3, there is theadvantage on the one hand of eliminating the effect of the centrifugalforce exerted on the liquid in the ladle and thus preventing anyswirling which could lead to the inclusion of impurities in the moltenmetal, and on the other hand of substantially reducing the energynecessary for carrying out this indexing, because in this configurationthe robot has a minimum moment of inertia about the shaft 3.

When the indexing operation has been carried out, the rotation of thearm 9 is caused to continue, by means of the cylinder 18 and cylinder14, until the hinge 13 is aligned with the hinges 12 and 15. Beyondthis, the arm 9 either begins its descent if the hinges 12 and 15 are ona vertical line, or it terminates its elevation to be followed by alowering movement if the hinge 15 is displaced to the left, in FIG. 1,of the vertical passing through the hinge 12, and is driven only by thecylinder 18 as the cylinder 14 then operates as a brake for saiddescent. In this respect, said cylinder 14 is always fed in the sense ofretracting its rod 14a. Such an arrangement advantageously compensatesthe increase in the torque applied to the arm 9 during its descent, dueto the weight. During this time, the ladle 11 passes between the twobranches of the end 9a of the arm, which are sufficiently spaced apartto allow this passage. In this respect, an arm in the form of a singlebeam could be provided by laterally offsetting at least part of itslength relative to the hinge 10 and hinge 12, to allow lateral passageof the ladle 11. When the arm has arrived above the mould, the feed tothe cylinder 14 is reversed, to create a force for positioning the ladle11 on the mould casting mouth. Casting is controlled by opening theladle using its stopper rod, and when casting is terminated, the feedsto the cylinder 14 and cylinder 18 are again reversed to return theempty ladle 11 directly over the shaft 3. A new angular indexingoperation is then carried out by means of the cylinders 6a and 6b. Thisindexing can be different from the initial one if in the vicinity of therobot there has been provided a second furnace from which the metal canbe ladled, or a maintenance station for the ladle. The arm is then madeto descend again, with the cylinder 14 again performing its brakingfunction.

It should be noted that the role of the cylinder 14 can be varied byvarying the pressure which it receives during its operation, so that itperforms either a compensation function or maintains the ladle on themould.

During the raising of the arm 9 with the ladle full, the secondary arm20 accompanies it by the effect of the spring 23. As it approaches thevertical, the arm 20 is retained by the stop 25 so that it does notobstruct the positioning of the ladle on the mould. On its return, thesecondary arm 20 is lowered by the stop 24 during the descent of the arm9, so that the probes 22 become disposed in their active position. Thesein effect govern the plunging of the ladle into the bath.

It can therefore be seen that the invention makes use of simple meansfor constructing a robot of great strength. Moreover, the loopingtransfer of the casting ladle frees the floor areas and working stationssituated around the robot, while increasing reliability. Finally, by itsdesign, the energy necessary for its operation is reduced, and the timesfor the operations can advantageously be shortened.

POSSIBLE INDUSTRIAL APPLICATIONS

The invention finds important application in the foundry field.

It is not limited to the description given, but instead covers allmodifications which can be made to it without leaving the scope of theinventive idea. Thus, instead of a hinged ladle, the arm 9 can be fittedwith a support member hinged at 10 to its end 9a for receiving cores,moulds, castings withdrawn from moulds etc.

In this respect, the robot is nothing other than a device formanipulating foundry accessories from one or more charging positions toone or more discharge positions disposed within or to the side of saidfurnaces or moulds.

Thus, for example, an installation could be imagined comprising tworobots, the first being used between a furnace and the pouring intomoulds moving on one or more conveyors passing in its vicinity, and thesecond robot being used to manipulate castings withdrawn from the mouldsbetween said conveyors and one or more conveyors for removing saidcastings, the moulds being returned in the direction of the first robot.

I claim:
 1. A transfer device comprising a frame including a fixed partand a mobile part rotatable relative to said fixed part about a verticalshaft, an arm hinged at one end thereof to the top of said mobile partabout a horizontal pin and provided at its other end with means forattaching a load, means for rotating the mobile part of the framerelative to its fixed part, means for driving the arm about saidhorizontal pin, said driving means arranged between the mobile part ofthe frame and said arm in such a manner that the arm can rotate throughapproximately 180° and wherein said arm is arranged such that theattachment means is driven along a substantially vertical semicircleabove a horizontal plane passing through said horizontal pin and saidvertical semicircle including the axis of said vertical shaft, and meansfor controlling said rotating means, said control means being operativewhen said attachment means is directly above the axis of said verticalshaft.
 2. A device as claimed in claim 1, wherein said driving meanscomprises a cylinder rigid with the mobile part, said cylinder having arod of rack configuration cooperating with a pinion rigid with the arm.3. A device as claimed in claim 2, wherein along said arm, a secondaryarm is hinged about said horizontal pin and is provided at its end withproximity detection probes.
 4. A device as claimed in claim 3, whereinsaid secondary arm is biased against a stop by a spring member in asubstantially vertical position, said first mentioned arm being capableto drive said secondary arm against the bias of said spring member.
 5. Adevice as claimed in claim 3, wherein said proximity probes are adaptedfor detecting the level of a bath in a furnace.
 6. A device as claimedin claim 1, wherein said one end of said arm extends beyond saidhorizontal pin relative to the frame and is hinged to a rod of apneumatic compensating cylinder, said cylinder being hinged to themobile part of the frame.
 7. A device as claimed in claim 6, whereinsaid cylinder is operative such that said rod is retractable, therebycomprising auxiliary drive means for raising said arm and means forbraking said arm when said arm lowers.
 8. A device as claimed in claim 7adapted for withdrawing, transferring and pouring a molten metal,wherein said attachment means is a casting ladle, and wherein saidpneumatic cylinder is operated at the moment of pouring in the directionof extraction of the rod to maintain the casting ladle on the mould. 9.A device as claimed in claim 8 further including means for maintainingthe orientation of the casting ladle vertical, said maintaining meanscomprising an endless chain disposed between a first pinion coaxial withsaid horizontal pin of the arm and rigid with the mobile part of theframe, and a second pinion coaxial with a hinge of said ladle on the armand rigid with said ladle.